Buggy code:
public class SyncStrategy { protected final Logger log = LoggerFactory . getLogger ( getClass ( ) ) ; private final boolean SKIP_AUTO_RECOVERY = Boolean . getBoolean ( "solrcloud.skip.autorecovery" ) ; private final ShardHandler shardHandler ; private ThreadPoolExecutor recoveryCmdExecutor = new ThreadPoolExecutor ( 0 , Integer . MAX_VALUE , 5 , TimeUnit . SECONDS , new SynchronousQueue < Runnable > ( ) , new DefaultSolrThreadFactory ( "recoveryCmdExecutor" ) ) ; private volatile boolean isClosed ; private static final HttpClient client ; public SyncStrategy ( ) { } private static class ShardCoreRequest extends ShardRequest { String coreName ; public String baseUrl ; } public boolean sync ( ZkController zkController , SolrCore core , ZkNodeProps leaderProps ) { } private boolean syncReplicas ( ZkController zkController , SolrCore core , ZkNodeProps leaderProps ) { boolean success = false ; CloudDescriptor cloudDesc = core . getCoreDescriptor ( ) . getCloudDescriptor ( ) ; String collection = cloudDesc . getCollectionName ( ) ; String shardId = cloudDesc . getShardId ( ) ; if ( isClosed ) { log . info ( "We<seq2seq4repair_space>have<seq2seq4repair_space>been<seq2seq4repair_space>closed,<seq2seq4repair_space>won't<seq2seq4repair_space>sync<seq2seq4repair_space>with<seq2seq4repair_space>replicas" ) ; return false ; } try { success = syncWithReplicas ( zkController , core , leaderProps , collection , shardId ) ; } catch ( Exception e ) { SolrException . log ( log , "Sync<seq2seq4repair_space>Failed" , e ) ; } try { if ( isClosed ) { log . info ( "We<seq2seq4repair_space>have<seq2seq4repair_space>been<seq2seq4repair_space>closed,<seq2seq4repair_space>won't<seq2seq4repair_space>attempt<seq2seq4repair_space>to<seq2seq4repair_space>sync<seq2seq4repair_space>replicas<seq2seq4repair_space>back<seq2seq4repair_space>to<seq2seq4repair_space>leader" ) ; return false ; } if ( success ) { log . info ( "Sync<seq2seq4repair_space>Success<seq2seq4repair_space>-<seq2seq4repair_space>now<seq2seq4repair_space>sync<seq2seq4repair_space>replicas<seq2seq4repair_space>to<seq2seq4repair_space>me" ) ; syncToMe ( zkController , collection , shardId , leaderProps , core . getCoreDescriptor ( ) ) ; } else { <START_BUG> log . info ( "Leader's<seq2seq4repair_space>attempt<seq2seq4repair_space>to<seq2seq4repair_space>sync<seq2seq4repair_space>with<seq2seq4repair_space>shard<seq2seq4repair_space>failed,<seq2seq4repair_space>moving<seq2seq4repair_space>to<seq2seq4repair_space>the<seq2seq4repair_space>next<seq2seq4repair_space>canidate" ) ; <END_BUG> } } catch ( Exception e ) { SolrException . log ( log , "Sync<seq2seq4repair_space>Failed" , e ) ; } return success ; } private boolean syncWithReplicas ( ZkController zkController , SolrCore core , ZkNodeProps props , String collection , String shardId ) { } private void syncToMe ( ZkController zkController , String collection , String shardId , ZkNodeProps leaderProps , CoreDescriptor cd ) { } private boolean handleResponse ( ShardResponse srsp ) { } private void requestSync ( String baseUrl , String replica , String leaderUrl , String coreName ) { } public void close ( ) { } private void requestRecovery ( final ZkNodeProps leaderProps , final String baseUrl , final String coreName ) throws IOException , SolrServerException { } public static ModifiableSolrParams params ( String ... params ) { } }

Fix:
log . info ( "Leader's<seq2seq4repair_space>attempt<seq2seq4repair_space>to<seq2seq4repair_space>sync<seq2seq4repair_space>with<seq2seq4repair_space>shard<seq2seq4repair_space>failed,<seq2seq4repair_space>moving<seq2seq4repair_space>to<seq2seq4repair_space>the<seq2seq4repair_space>next<seq2seq4repair_space>candidate" ) ;